328 SMITH. 



probable that the lignitic series of Cebu was deposited, and the contorted in- 

 durated strata, which in other localities also carry black lignite relatively free 

 from water, should be referred provisionally to this period. Whether the num- 

 mulitie limestone found at Binangonan is Eocene seems to me to be an unsolved 

 question. After the Cebuan lignitic epoch a great uplift and folding took place, 

 and this may have been a detail of the late Eocene movement which so profoundly 

 modified Asia and Europe. It must have brought about temporary continuity of 

 land area between Borneo and Luzon. Somewhere about the middle of the 

 Miocene the country sank to a low level. Many of the present islands must then 

 have been far below water, while Luzon and Mindanao were represented by 

 groups of islets. Observations appear to suggest that the Agno beds represent 

 the basal conglomerate formed at this subsidence. A slow rise began again dur- 

 ing the later Miocene, and may have continued to the present day without in- 

 version, yet the actual distribution of living forms is such as to give some 

 ground for believing that, at some intermediate period, the Islands were a little 

 higher than they now are, but sank again only to rise afresh. The diorites and 

 associated massive rocks, including their tuffs, may have made their appearance 

 about the close of the Paleozoic. The less siliceous of these rocks seem to have 

 followed the more siliceous intrusions as a whole. The gold deposits, and perhaps 

 other ores, are so associated with these massive rocks as to indicate a genetic 

 relation. The neovolcanic period began as early as the highest Miocene horizon, 

 and very probably at the Post-Eocene upheaval. If the semiplastic marls of Cebti 

 are all Miocene, the earlier andesitic rocks, at least, date back nearly to the great 

 upheaval. Among these rocks, also, there is sometimes a tendency for the basalts 

 to follow the andesites, but the one dacite found at Corregidor is later than the 

 andesites of that island. The relation of the trachytes to the andesites is not 

 certain, but the sanidine rock is probably the earlier. A very large part of the 

 neovolcanic ejecta has fallen into water and been rearranged as tuffaceous plains. 

 The volcanic vents appear to me to occur rather on a network of fissures than 

 on a system of parallel diaclases, and the volcanic activity is to be regarded as a 

 thermal manifestation of the energy of upheaval. 



As regards the history of the Islands prior to the Eocene, our knowl- 

 edge is in the same state to-day as it was when Becker wrote his summary. 

 Furthermore, I am not as hopeful as I was at the beginning of my in- 

 vestigations that Mesozoic and Paleozoic strata will be found. They may 

 by chance be encountered in deep wells, in a deep shaft, or in some canon 

 of the cordillera on the Island of Luzon. The oldest fossil I have seen 

 from the Philippines is Nummulites niasi, which is typically Oligocene. 

 Lepidocyclina, Cycloclypeus, Globigerina, Heterostegina, Lithothamnium. 

 etc., are abundant. The Binangonan limestone is Oligocene. 



It is probable that the Islands have sunk at least once after the 

 formation of the Agno beds (Bued Eiver conglomerate) . This fact is 

 attested by the presence of an indurated coral reef above the latter at a 

 present elevation of over 1,300 meters. This old reef is exposed in 

 Trinidad Gap a few miles north of Baguio. It seems quite probable 

 that the main period of ore deposition followed the Miocene uplift and 

 ended before that of the later sedimentaries. The gold-bearing veins 

 in Masbate cut across andesites and diorites indiscriminately. They 



